This item is technically not needed to crack safes, however, you will not keep the look if you do not have this or one of the other size bags with you. Loot bags come in:
Typically, a safe will fill the bag 0.5-1%. This means that it will require 102-198 safes to fully fill your loot bag.
A full loot bag can be fenced for 182,950-208,900 Thieving
experience, 676-757 Pilfer points, and 294,750-393,250 coins
Note that you must have the previous size loot bag before you can purchase the next upgrade. If lost or destroyed, you can obtain the lost size bag from the Safe-cracking trainer
To hold an intrepid thief's loot.